Setting The Urgent Pointer Policy - Cisco 4700M Configuration Manual

Configuring a Connection Parameter Map for TCP/IP Normalization and Termination

Setting the Urgent Pointer Policy

Cisco 4700 Series Application Control Engine Appliance Security Configuration Guide
4-24
Chapter 4
If the Urgent control bit (flag) is set in the TCP header, it indicates that the Urgent
Pointer is valid. The Urgent Pointer contains an offset that indicates the location
of the segment that follows the urgent data in the payload. Urgent data is data that
should be processed as soon as possible, even before normal data is processed.
The ACE permits you to allow or clear the Urgent flag. If you clear the Urgent
flag, you invalidate the Urgent Pointer.
The ACE clears the Urgent flag for any traffic above Layer 4. If you have enabled
TCP server connection reuse (see the Cisco 4700 Series Application Control
Engine Appliance Server Load-Balancing Configuration Guide, Chapter 2,
Configuring Traffic Policies for Server Load Balancing), the ACE does not pass
the Urgent flag value to the server.
To set the Urgent Pointer policy, use the urgent-flag command in parameter map
connection configuration mode. The syntax of this command is as follows:
urgent-flag {allow | clear}
The keywords are as follows:
allow—(Default) Permits the status of the Urgent flag. If the Urgent flag is
•
set, the offset in the Urgent Pointer that indicates the location of the urgent
data is valid. If the Urgent flag is not set, the offset in the Urgent Pointer is
invalid.
clear—Sets the Urgent flag to 0, which invalidates the offset in the Urgent
•
Pointer and allows the segment.
For example, to clear the Urgent flag and allow the segment, enter:
host1/C1(config-parammap-conn)# urgent-flag clear
To reset the ACE behavior to the default of allowing the Urgent flag, enter:
host1/C1(config-parammap-conn)# no urgent-flag
Configuring TCP/IP Normalization and IP Reassembly Parameters
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